The ACB had questioned Delhi Chief Minister Arvind Kejriwal's political adviser Vibhav Patel in the alleged water tanker scam on May 17.

The ACB had summoned Patel on May 14 after the sacked Delhi Water minister told the ACB that two persons, Patel and Ashish Talwar who were close to Kejriwal, were responsible for the delay in action in the water tanker scam.

However, during his questioning, Patel had denied any involvement in the matter, following which the agency has called Mishra for cross-questioning.

Mishra had earlier recorded his statement with the ACB on May 11, after he submitted evidence in support of his allegations.

The Rs 400-crore water tanker scam involving alleged favouritism shown in the allotment of contracts to private water tanker operators supplying water to areas falling outside the Delhi Jal Board's network happened under the previous Congress government in the city.